Once underground access is commenced through a portal or shaft for a new mine, diamond drill crews begin drilling from the first available underground location to allow geologists to better define the ore body so that the design of the mine can be optimised. Therefore exploration drilling usually occurs in advance of the mine development, and typically the exploration drill holes range from horizontal to downward dipping to delineate the ore body beneath and to the side of the main access.
When these exploration drill holes are abandoned, they leave an open hole between the main access and the ore body location which will at some stage be advanced upon. In some cases high pressure water may be encountered during mining, and it is therefore necessary to block these abandoned drill holes to prevent the high pressure water from entering the mine.
Commonly-owned, co-pending Australian Patent Application No 2011301781 discloses a clay plug for sealing water flow from a drill hole. The clay plug 40 of AU2011301781 comprises an elongate sleeve 42 of porous material containing a volume of clay material 44 which in this instance is bentonite clay (although other clays may also be suitable). The clay plug 40 further includes a liner 46 of water-soluble material, and a substantially solid central core 48 running substantially the length of the plug. The advantage of using bentonite clay as the “grouting” material in this plug is that bentonite clay slowly expands and seals when in contact with water. The contents of AU2011301781 are incorporated herein by reference.
Diamond drill holes are drilled by rotation only drill rigs, and as a result drill a hole through hard rock which only varies slightly in diameter with drill bit wear. Due to this small variation in diameter, it is possible to use close tolerances when designing and installing tools or implements into a diamond drill hole.
The present invention was developed with a view to providing a plug for plugging a drill hole that exploits this close tolerance by using an O-ring to provide a braking action against the wall of the diamond drill hole. The plug is prevented from being pushed out of the diamond drill hole by the braking action of the O-ring. Whilst the plug is designed to resist significant water pressure and water flow when installed into a diamond drill hole, it will be understood that the O-ring plug may also have wider application.
References to prior art in this specification are provided for illustrative purposes only and are not to be taken as an admission that such prior art is part of the common general knowledge in Australia or elsewhere.